Leaf-spring.



C. P. SCHWARZ.

LEAF SPRING. APPLICATION FILED FEB. 4. Isle.

1,219,592. v. Pate11ted`Mar.20,l9l7.

.pf2/Zwaag other purposes.

CONSTANTINE PBOTEUS SCHWARZ, OF CLEVELAND, OHIO. D

Specication'of Letters '.Patent.

Patented Mar. 20, 19M'.

Application filed February 4, 1.916. Serial No. 76,109.

To all whom t may concern:

Be 1t known that I, CoNs'rANTiNE PRo'rEUs SCHWARZ, a citizen of theUnited States, re-

siding at Cleveland, in the county of Cuyahoga and State of Ohio, haveinvented a new and useful Improvement in Leaf- Springs, of which thefollowing is a specifin cation.

This invention relatesto improvements in leaf springs of the kind usedon vehicles, buffers or draft gears for railroad cars or It-is wellknown that a leaf spring has a certain amount of ability to absorbshocks due to the friction between the leaves, and that if the frictionbetween the leaves is increased, the shoclr absorbing ability isincreased so that the recoil of the spring is reduced.

The object of the invention is to provide a leaf spring of this kind ofimproved construction in which the shock absorbing ability of the springis increased without materially increasing the weight of the i spring.This is accomplished by placing layersfor inserts of frictional materialbetween the spring leaves so that the friction between the spring leavesand the inserts consumes the energy which would otherwise be used incausing a recoil of the spring, and by proportioning the inserts in sucha manner that the recoil of the spring is substantially, if notentirely, eliminated.

In the accompanying drawings:

Figure 1 is a Aside `eleva/tion of a leaf spring embodying theinvention.

Fig. 2 is a transverse sectional eleva-tion thereof, on an enlargedscale, on line 2-2, Fig. 1. I

It is well known that energy is the product of force and distancetraveled, and that force is the product of pressure and the coeflicientof friction, so that it may be said that the energy absorbed in aspringis the product of pressure, co-eiiicient of friction and distancetraveled. This may be eX- pressed in the following formula:`

E=P.f.s., E representing the energy which must be absorbed by the springto produce a periodicity, P the pressure acting on the engaging faces ofthe spring leaves and inserts, f

faces. Hence the energy absorbed in a spring may be increased byincreasing the co-eflicient of friction or by increasing the distancetraveled, or in other words, the amount of movement between the parts ofthe spring. The construction shown in the drawings shbws a springconstructed to have a large lamount of movement between the parts of thespring so that substantially all of the energy stored in the spring whenthe same is subjected to a shock is dissipated while the spring isreturning to its normal position.

A represents the upper leaf of a spring which may be provided withloopedf end portions or eyes a for securing the spring to the usualshackles or bolts of a vehicle.v A A2 A3 and A4 represent the usualsuperimposed spring leaves of varying lengths secured together to formthe leaf spring. B B B2 and B3 represent insertsor layers of friciinsnenn arriba.'

tional material which are placed between adrelative movement of ,thespring leaves is greater than with thin ones.

The thickness of the inserts in order tovconstruct an aperiodio spring,depends largelyupon the coefcient of friction, but should be underordinary conditions about one and one-half times the thickness of thespring leaves. The spring leaves and inserts may be secured together byany suitable means, such, for eX- ample, as clips'or shackles C.

In the leaf spring described, the relative displacement between the.lcontacting parts of the spring? leaves and inserts is increased byincreasing the thickness of the inserts, and consequently the energyabsorbed by the spring is also increased. The increased shock absorbingabilityV of the spring may thus be obtained by increasing thesize orbulk of the spring with very small increase in weight. The frictionbetween the spring leaves and the inserts also tends to stilfen thespring somewhat, so that somewhat 4 lighter spring leaves may be used,when the spring is provided With inserts than could otherwise be used.In producing' a spring of this kind, the shock absorbing ability of.

the same'can easily be varied by changing the thickness of the inserts.In this manner it is possible to produce in springs of this kind anydesired degree of shock absorption.

I claim as my invention:

l. A leaf spring comprising a plurality of spring leaves, and layers offrictional material inserted between adjacentr spring leaves differingin character from the spring leaves, said layers being of greaterthickness than the leaves of said spring to cause a large relativemovement of the component 'parts of the spring.

2. A leaf spring comprising a plurality of spring leaves, and layers offrictional material inserted between adjacent spring leaves differing incharacter from the spring leaves to increase the relative displacementof the contacting parts of the spring when deflected, said layers beingof a thickness substantially one and one-half times the thickness of theleaves.

3. A leaf spring having a plurality of spring leaves and in which saidleaves are separated b layers of iiekible material of lower speci cgravity than the leaves, said layers being free at their ends to movel0ngitudinally with regard to said leaves and ncreasing the bulk of thespring to produce a large and unrestricted relative movement between theparts of the spring Without ma terially increasing the Welght of thespring,

said layers being sufficiently flexible so that.

said layers of themselves offer substantially no material resistance tothe deflections of the spring.

Witness my hand, this 1st day of February, 1916.

. CONSTANTINE PROTEUS SGHWARZ,

Witnesses:

FLEMING H. CREW, DWIGHT E. WERTZ.

